In today's designs of a chip, multiple voltage domains are usually required, and the voltages of digital circuits, analog circuits and external interface circuits are all different. An effective way to supply power to these circuits is a linear voltage regulator. At present, a universal linear voltage regulator, as shown in FIG. 1 of Patent CN106200741A entitled Current Sink Load Circuit and Low-Dropout Linear Voltage Regulator, consists of a bandgap reference source, an error amplifier, a power transistor and a sampling circuit. An important characteristic of voltage regulators of this type is to maintain the stability of an output voltage under various conditions. The bandgap reference source used for a reference voltage ensures a very little change in the reference voltage under various conditions, so that the voltage of the linear voltage regulator remains stable. In practical applications, if a threshold voltage of an MOS transistor is reduced at high temperature, the actual operating power required by a circuit can be reduced. However, a leakage current of the chip increases because of the constant output of the voltage regulator.
The power consumption of a digital circuit consists of dynamic power consumption, short-circuit current and static leakage current of a circuit switch, and an effective way to reduce such three kinds of current is to reduce a supply voltage. In conventional linear voltage regulator circuits, a minimum operating voltage required in the worst case is set as a threshold voltage so as to ensure that the chip can operate under various process conditions, thus resulting in high supply voltage and increased power consumption of the digital circuit.
Therefore, great improvements to the existing technology are urgently needed.